We have a HP SAN which we are trying to ditch in order to migrate the data to a Windows Server VM for better resilliency
At the moment the data is roughly 15TB but does grow daily by 1-5GB so there will be future expansion
In terms of VMware and Veeam what is the best approach to this? I was thinking either an initial single VMDK 15TB GPT Simple volume or 3 VMDK x 5TB GPT Dynamic volumes then span across these but not quite sure as to the specific pros and cons of each method...
If it were me, I'd avoid dynamic disks at all costs whenever possible. If you're on a VMware version that can size a 15TB disk, I'd do that instead. I've never seen "good" results from Dynamic Disks in a virtual environment and I think just puts you in a fragile spot.
I would opt for dynamic disks only if there was a real necessity to use one of their specific abilities, for example if you're looking for more flexibility from volume management perspective.
The setup with 3 different VMDK-s gives you a possibility to backup all disks in parallel as long as you have enough available slots on repository and proxy.
Although, it does not make sense to split disks if you're sure that the duration of job with VM having the single disk will fit your backup window.